For what its worth, I have it the other way around. 1.5 years with an Xperia T and stock fw, upgraded to 4.3 some months ago, no reboot or overheating (to the effect it would crash) ever. Now, with a stable CM 10.2 I had 4 spontaneous reboots in that one week, even without interaction. Also had several occasions as described in posts above: a rather hot device that after a few minutes of active GPS would not fix a position any longer, and while charging and using GPS is almost too hot to touch. I considered going back to stock.
My progressive attempt at a countermeasure now: going nightly, the 20140611 just came out. Will tell you how it goes.
Edit: No, 20140611 also has this bug, no usable GPS.